1. Field of the Invention
The present invention relates to an image outputting apparatus, and particularly to the technique of displaying images in multi-level tones.
2. Description of the Related Art
Among image outputting apparatus, one type of apparatus can vary the concentration of color in multiple levels for each unit output area, and the other type of apparatus can vary the concentration only in two levels. In case the output image needs to be toned in colors as in a landscape or portrait, rather than a literal text, the former type of apparatus outputs the image with a concentration substantially the same as the original image for each unit output area selected suitably from available multi-level concentrations, and the latter type of apparatus outputs the image based on the area toning method. The area toning method expresses a tone in terms of the number of output units to be colored within a matrix assumed to be constructed from m.times.n output units. The former type of apparatus can produce an image of high resolution with precise toning. The latter type of apparatus establishes a tone for each area made up of multiple unit output areas and, although the resolution is low, it features to produce design-oriented images and images with the emergence of a moire pattern.
In the conventional apparatus having output means for outputting an image by varying the concentration of unit output areas in multiple levels, when it is needed to output an image in toned colors, a number of types of outputs are produced only with concentrations of the maximum number of levels available by the apparatus and an output in a smaller number of levels is not produced.